diff --git a/lib/devise/controllers/helpers.rb b/lib/devise/controllers/helpers.rb
index 834226e56f..51b01cf909 100644
--- a/lib/devise/controllers/helpers.rb
+++ b/lib/devise/controllers/helpers.rb
@@ -110,6 +110,8 @@ def sign_in(resource_or_scope, *args)
 
         if options[:bypass]
           warden.session_serializer.store(resource, scope)
+        elsif warden.user(scope) == resource && !options.delete(:force)
+          # Do nothing. User already signed in and we are not forcing it.
         else
           warden.set_user(resource, options.merge!(:scope => scope))
         end
@@ -199,13 +201,7 @@ def sign_in_and_redirect(resource_or_scope, *args)
         options  = args.extract_options!
         scope    = Devise::Mapping.find_scope!(resource_or_scope)
         resource = args.last || resource_or_scope
-
-        if warden.user(scope) == resource
-          expire_session_data_after_sign_in!
-        else
-          sign_in(scope, resource, options)
-        end
-
+        sign_in(scope, resource, options)
         redirect_for_sign_in(scope, resource)
       end
 
diff --git a/test/controllers/helpers_test.rb b/test/controllers/helpers_test.rb
index 83578a6abe..ea93ec682a 100644
--- a/test/controllers/helpers_test.rb
+++ b/test/controllers/helpers_test.rb
@@ -90,16 +90,32 @@ def setup
 
   test 'sign in proxy to set_user on warden' do
     user = User.new
+    @mock_warden.expects(:user).returns(nil)
     @mock_warden.expects(:set_user).with(user, :scope => :user).returns(true)
     @controller.sign_in(:user, user)
   end
 
   test 'sign in accepts a resource as argument' do
     user = User.new
+    @mock_warden.expects(:user).returns(nil)
     @mock_warden.expects(:set_user).with(user, :scope => :user).returns(true)
     @controller.sign_in(user)
   end
 
+  test 'does not sign in again if the user is already in' do
+    user = User.new
+    @mock_warden.expects(:user).returns(user)
+    @mock_warden.expects(:set_user).never
+    @controller.sign_in(user)
+  end
+
+  test 'sign in again when the user is already in only if force is given' do
+    user = User.new
+    @mock_warden.expects(:user).returns(user)
+    @mock_warden.expects(:set_user).with(user, :scope => :user).returns(true)
+    @controller.sign_in(user, :force => true)
+  end
+
   test 'sign in accepts bypass as option' do
     user = User.new
     @mock_warden.expects(:session_serializer).returns(serializer = mock())